People with MCI often have difficulties with memory, but these are not bad enough to be defined as dementia. Some people diagnosed with MCI will go on to develop dementia, some will remain stable over time and a few people will improve and no longer have any problems. Although it can be the first sign of dementia, sometimes MCI will be diagnosed as a result of another condition such as anxiety or depression.

There are various types or causes of dementia, and it is possible for someone to have a combination of these - this can make an accurate diagnosis more difficult.

BRACE funds research into the most common types of dementia which are as follows:

Alzheimer's disease

Alzheimer’s disease is the most common form of dementia, responsible for about 62% of cases.

The first sign is short term memory loss. This develops to further symptoms including more severe memory problems, confusion, disorientation, personality changes and problems with language and speech.

Alzheimer’s disease affects the brain physically. Proteins build up in an abnormal way in the brains of those with Alzheimer’s disease. Amyloid-β deposits known as ‘plaques’ build up around brain cells, and tau ‘tangles’ form inside brain cells.

The result is damage to brain cells and a loss of connections between them. The brain becomes smaller than normal.

Alzheimer’s disease is progressive, meaning it gets worse over time. Because it develops slowly, it can often be difficult to recognise.

Vascular dementia (VaD)

Vascular dementia is the second most common type of dementia, responsible for 17% of cases.

Diseased blood vessels mean that the blood supply to parts of the brain is reduced. This causes death of brain cells, leading to problems with memory, thinking and reasoning.

At least 10% of people with dementia are diagnosed with mixed dementia, where both Alzheimer’s disease and vascular disease are causes of dementia.

Dementia with Lewy bodies (DLB)

DLB accounts for about 4% of dementia cases.

DLB shares symptoms with both Alzheimer’s disease and Parkinson’s disease.

Lewy bodies are deposits of a protein called α-synuclein in nerve cells, and are associated with cell damage. They are the underlying cause of several progressive diseases affecting the brain and nervous system, including dementia with Lewy bodies and Parkinson’s disease.

Symptoms of DLB depend upon where the Lewy bodies are in the brain. If they are in the outer layers of the brain, this is usually associated with problems in mental abilities.

About one third of Parkinson’s disease patients eventually develop dementia.

Frontotemporal dementia (FTD)

FTD is less common (2% of dementia cases), but is a significant cause of dementia in those under 65 years of age.

Nerve cells in the frontal and/or temporal lobes of the brain die and the pathways that connect them change. This leads to symptoms including changes in personality and behaviour, and difficulties with language.

Autopsy studies show that the death of nerve cells in the frontal and temporal lobes is linked to clumps of abnormal proteins inside cells, including tau. Tau may take the form of Pick bodies, giving frontotemporal dementia its original name of Pick’s disease.

Dementia is a set of symptoms relating to a loss of cognitive ability, with symptoms including memory loss and issues with thinking, problem solving and language.

Dementia is caused when the brain is damaged by diseases, which may include Alzheimer's disease. You may hear dementia described as a degenerative condition, meaning that the normal functioning of the brain is gradually being reduced over time.

There are many degenerative conditions that affect the brain - each one has its own signs and symptoms and some, but not all, may involve dementia.

Unfortunately none of the current drugs is a cure for dementia, but they can temporarily slow down the progression of the symptoms of Alzheimer’s disease.

All these drugs have to be prescribed by consultant therefore it is necessary for the GP to refer a patient to a specialist for assessment for treatment on the NHS. Private prescriptions can be obtained through a consultant, GP or private hospital but the costs are very high and a proper assessment of the person should still be made.

There are four drugs available for use in Alzheimer's disease: Aricept, Exelon and Reminyl are used in people with mild to moderate disease and Ebixa is used for people in the middle to late stages of the disease.

Aricept, Exelon and Reminyl all work in a similar way - by preventing the breakdown of the chemical messenger acetylcholine which is less abundant in Alzheimer's disease. This allows better communication between undamaged brain cells and temporarily stabilises or improves brain function. However, they don't work for everyone and one drug may suit an individual more than another.

Ebixa works in a different way by modulating the levels of certain molecules responsible for the memory and learning processes in the brain.

A proper medical assessment of someone who appears to be developing the symptoms of dementia is required because:

The cause of the person's problems may be treatable.

It means that the most appropriate care and advice can be provided. The earlier a diagnosis is made, the more effective a treatment can be because the brain has is likely to have suffered less damage in the earlier stages of disease.

It allows access to support services geared to the person with dementia and their carers.

It allows those with dementia to make plans for the future, along with their families.

Placing items in the wrong places such as the iron in the freezer and then being unable to find them again

Rapid, unexplained mood swings

Changes in the person's normal responsibility

Becoming passive or reluctant to get involved in activities

It is important to realise that these behavioural changes may occur in other forms of dementia that may be treatable by the doctor such as an infection, anaemia, or thyroid problems or which have a different cause such as excessive alcohol consumption. If you, or someone you know is experiencing any of these symptoms, please see a doctor for a proper diagnosis and help.

It is now clear that there is no single cause of dementia but whatever causes the disease in each person, the outcome is the same - progressive decline of brain function.

The following have been suggested as possible causes: environmental pollution, viruses, aluminium, heredity, repeated head injury (e.g. boxing) or even too little use of the brain. Indeed, all of them could contribute to progression of dementia but not all will occur in every case.

The two strongest risk factors for developing Alzheimer’s disease are age and having a close relative who is affected. This has led to an increase in the number of research programmes examining the genetic background of those with Alzheimer's disease. However, it is still not possible to absolutely predict who will develop Alzheimer's disease, even if a family member has already been diagnosed.

Our brains are responsible for everything we do, think or feel and it keeps all this functioning by passing messages to different areas of our brain responsible for different things.

The message is sent along networks of brain cells via chemical messengers. If these networks are disrupted, the messengers can't get through to deliver their instructions and the brain gradually stops working properly.

In Alzheimer's disease problems are thought to be caused by protein deposits called plaques and tangles that slowly develop over time. Plaques appear as disc-like collections of debris around a central core of a protein called amyloid and tangles are bundles of abnormal fibre-like material (called tau) that look like balls of string. As more and more of these plaques and tangles develop they cause brain cells to die and the brain to become smaller than normal.